Install these Union-Strainers™ upstream of the HVAC Air-Trap™ to prevent rocks, screws, nuts, etc. from getting into the trap mechanism. Inexpensive and easy to install and service.
Also, a convenient way to prevent unwanted creatures from entering the terminus of the drain line, like snakes, rats, lizards, and insects. Just cap off the end of the drain with a Union-Strainer™.
schedule 40, white PVC